[Help] Hissing sound from fanless Raspberry Pi 4

The linked file is a recording of a hissing sound that my Raspberry Pi 4 started to make sometime during the last 24 hours. Another symptom is that the power on and CPU activity LEDs are out. It is not running hot. It doesn’t have an internal fan. It is being cooled by six PC chassis fans. It is running OpenWRT. It has been pumping Linux ISOs in and out non stop for about four months.

I have tried cleaning it by dedusting it. I have also tried rebooting it. While rebooting, it squeals like a mouse, like it was suffering but the LEDs function properly. As soon as it loads user space though and resume routing, they turn off and the hissing sound continues.

Here are some system logs with severities warning and error. As you can see, the logs are from the 15th and I don’t think any of them pertain to the hissing sound and/or the LEDs.

WARNING [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196065] pci_bus 0000:01: supply vpcie3v3 not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196201] pci_bus 0000:01: supply vpcie3v3aux not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196257] pci_bus 0000:01: supply vpcie12v not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] user.warn: [ 7.225917] urandom-seed: Seeding with /etc/urandom.seed [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.327998] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned. [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.365104] brcmutil: loading out-of-tree module taints kernel. [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.780919] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin failed with error -2 [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.792642] brcmfmac mmc1:0001:1: Falling back to sysfs fallback for: brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin [May 15, 2026, 23:29:12 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry [May 15, 2026, 23:29:18 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry [May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: rfc9096: br-lan: piofile updated [May 15, 2026, 23:29:37 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:29:53 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:30:18 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! ERROR [May 15, 2026, 23:29:12 GMT+2] kern.err: [ 0.307942] bcm2708_fb soc:fb: Unable to determine number of FBs. Disabling driver. [May 15, 2026, 23:29:12 GMT+2] kern.err: [ 0.307968] bcm2708_fb soc:fb: probe with driver bcm2708_fb failed with error -2 [May 15, 2026, 23:29:12 GMT+2] user.err: [ 7.197094] insmod: module is already loaded - fat [May 15, 2026, 23:29:12 GMT+2] user.err: [ 7.204851] insmod: module is already loaded - vfat [May 15, 2026, 23:29:22 GMT+2] daemon.err: procd: Got unexpected signal 1

Judging by the squealing during reboot, I believe it to be either the CPU or memory, although I have never hears memory make sound, while CPUs, I have.

Hissing.m4a

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Hissing sound from fanless single board computer

The linked file is a recording of a hissing sound that my Raspberry Pi 4 started to make sometime during the last 24 hours. Another symptom is that the power on and CPU activity LEDs are out. It is not running hot. It doesn’t have an internal fan. It is running OpenWRT. It has been pumping Linux ISOs in and out non stop for about four months.

I have tried cleaning it by dedusting it. I have also tried rebooting it. While rebooting, it squeals like a mouse, like it was suffering but the LEDs function properly. As soon as it loads user space though and resume routing, they turn off and the hissing sound continues.

Here are some system logs with severities warning and error . As you can see, the logs are from the 15th and I don’t think any of them pertain to the hissing sound and/or the LEDs.

WARNING [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196065] pci_bus 0000:01: supply vpcie3v3 not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196201] pci_bus 0000:01: supply vpcie3v3aux not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 0.196257] pci_bus 0000:01: supply vpcie12v not found, using dummy regulator [May 15, 2026, 23:29:12 GMT+2] user.warn: [ 7.225917] urandom-seed: Seeding with /etc/urandom.seed [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.327998] snd_bcm2835: module is from the staging directory, the quality is unknown, you have been warned. [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.365104] brcmutil: loading out-of-tree module taints kernel. [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.780919] brcmfmac mmc1:0001:1: Direct firmware load for brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin failed with error -2 [May 15, 2026, 23:29:12 GMT+2] kern.warn: [ 8.792642] brcmfmac mmc1:0001:1: Falling back to sysfs fallback for: brcm/brcmfmac43455-sdio.raspberrypi,4-model-b.bin [May 15, 2026, 23:29:12 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry [May 15, 2026, 23:29:18 GMT+2] daemon.warn: dnsmasq[1]: no servers found in /tmp/resolv.conf.d/resolv.conf.auto, will retry [May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:29:21 GMT+2] daemon.warn: odhcpd[990]: rfc9096: br-lan: piofile updated [May 15, 2026, 23:29:37 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:29:53 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! [May 15, 2026, 23:30:18 GMT+2] daemon.warn: odhcpd[990]: No default route present, setting ra_lifetime to 0! ERROR [May 15, 2026, 23:29:12 GMT+2] kern.err: [ 0.307942] bcm2708_fb soc:fb: Unable to determine number of FBs. Disabling driver. [May 15, 2026, 23:29:12 GMT+2] kern.err: [ 0.307968] bcm2708_fb soc:fb: probe with driver bcm2708_fb failed with error -2 [May 15, 2026, 23:29:12 GMT+2] user.err: [ 7.197094] insmod: module is already loaded - fat [May 15, 2026, 23:29:12 GMT+2] user.err: [ 7.204851] insmod: module is already loaded - vfat [May 15, 2026, 23:29:22 GMT+2] daemon.err: procd: Got unexpected signal 1

Judging by the squealing during reboot, I believe it to be either the CPU or memory, although I have never hears memory make sound, while CPUs, I have.

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"Oh, and this audio filter removes hissing from the audio source."

"...."

"What? I saw your mouth move, but I did not hear anything."

"Exactly. I was hissing."

#hissing #audio #AudioFilter

Tux startled the absolute crap out of me. I was looking for something in the shed and when I walked out he was suddenly sitting behind the door, hissing at me. Little jerk 😂

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Crazy piss explosion after a long holding session

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A quotation from Horace

Like the Athenian miser, who was wont
To meet men’s curses with a hero’s front:
“Folks hiss me,” said he, “but myself I clap
When I tell o’er my treasures on my lap.”
 
   [Ut quidam memoratur Athenis
sordidus ac dives, populi contemnere voces
sic solitus: ‘populus me sibilat, at mihi plaudo
ipse domi, simul ac nummos contemplor in arca.’]

Horace (65-8 BC) Roman poet, satirist, soldier, politician [Quintus Horatius Flaccus]
Satires [Saturae, Sermones], Book 1, # 1, “Qui fit, Maecenas,” l. 64ff (1.1.64-67) (35 BC) [tr. Conington (1874)]

Sourcing, notes, alternate translations: wist.info/horace/75284/

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Sometimes this is all you need to say..,
#canadaGoose #cobrachicken #hissing #ottawa #morningwalk
this morning i would like to state the following: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh #hissing
That annoying ringing, buzzing, and hissing in the ear – a hearing specialist offers tips to turn down the tinnitus

One way to stop tinnitus before it starts: Wear hearing protection when in noisy places.

The Philadelphia Inquirer